2026 ICD-10-CM Diagnosis Code D55.9Anemia due to enzyme disorder, unspecified

ICD-10-CM Codes›D50–D89›D55-D59›D55

ICD-10-CM D55.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D55.9 is a billable ICD-10-CM diagnosis code for anemia due to enzyme disorder, unspecified. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 811 through 812. Coders also document this condition as anemia due to enzyme deficiency. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Hemolytic anemia.

D55.9 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 48 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 48, ESRD (V21) category 48, and ESRD (V24) category 48 for payment year 2026.

Code Identity

ICD-10-CM Code
D55.9
Billable Status
Yes — Valid for Submission
Code Describes
Anemia due to enzyme disorder, unspecified
Short Description
Anemia due to enzyme disorder, unspecified
Same as the full description in the CMS dataset.
Parent Code
D55
Anemia due to enzyme disorders

Code Classification

ChapterD50–D89Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
SectionD55-D59Hemolytic anemias
CategoryD55Anemia due to enzyme disorders
This CodeD55.9Anemia due to enzyme disorder, unspecified

Medicare Risk Adjustment (HCC)Billing

D55.9 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 48
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
PACE (CMS-HCC V22): HCC 48 · ESRD (V21): HCC 48 · ESRD (V24): HCC 48
ESRD V21 weights: 0.059 dialysis, 0.173–0.234 functioning graft · ESRD V24 weights: 0.063 dialysis, 0.192–0.358 functioning graft
Part D (RxHCC)
Not mapped
D55.9 does not risk-adjust in the RxHCC prescription drug model

Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Anemia due to enzyme deficiency
  • Anemia due to enzymopathy
  • Chronic non-spherocytic hemolytic anemia

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR BLD002
Hemolytic anemia
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Anemia due to Enzyme Disorder

    any form of anemia that results from the absence of, or the defective action of, any enzyme.

Patient EducationClinical

Anemia

If you have anemia, your blood does not carry enough oxygen to the rest of your body. The most common cause of anemia is not having enough iron. Your body needs iron to make hemoglobin. Hemoglobin is an iron-rich protein that gives the red color to blood. It carries oxygen from the lungs to the rest of the body.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert D55.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
282.3 Enzyme defic anemia NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D55.9Overview

What is the ICD-10 code for anemia due to enzyme disorder, unspecified?

The ICD-10-CM code for anemia due to enzyme disorder, unspecified is D55.9 (sometimes written as D559). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is D55.9 (Anemia due to enzyme disorders) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report anemia due to enzyme disorder, unspecified on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D55.9 group to?

When anemia due to enzyme disorder, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 811, 812, with relative weights from 0.9182 to 1.4043 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of D55.9?

Under the General Equivalence Mappings, anemia due to enzyme disorder, unspecified converts to ICD-9-CM 282.3 (enzyme defic anemia NEC). The mapping is approximate, so confirm the match fits the documentation.

Does D55.9 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. D55.9 mapped to HCC 48 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 48 (Coagulation Defects and Other Specified Hematological Disorders), ESRD (V21) category 48 (Coagulation Defects and Other Specified Hematological Disorders), and ESRD (V24) category 48 (Coagulation Defects and Other Specified Hematological Disorders).